Control system for domestic gas oven burners

Abstract

An oven burner control system having a manual rotary valve controlling gas flow to main and pilot burners and a solenoid operated valve controlling flow to the main burner, control circuit means embodying spark ignition means to ignite the pilot, means responsive to conduction through pilot flame to cut off spark ignition and permit operation of the solenoid valve, and variable resistance means responsive to oven temperature effecting cyclic operation of the solenoid valve. A control knob rotating with the manual valve varies the control point of said temperature variable resistance means and actuates a line switch to connect and disconnect the control circuit with a power source.

I claim: 
     
       1. In a burner control system, a pilot burner,   a main burner,   an electrical power source,   electrically operated means operative when energized to cause fuel to be supplied to said main burner,   circuit means including controlled solid state switching means connecting said electrically operated means across said power source,   a gating circuit for said switching means connecting one side of said power source to the controlling electrode of said switching means,   said gating circuit including first and second controlled solid state switching means,   circuit means responsive to the existence of pilot flame operative to effect conduction of said first switching means, and   temperature responsive circuit means operative to effect on and off conduction of said second switching means,   said temperature responsive means comprising:   temperature variable resistance means responsive to change in ambient temperature of a space heated by said main burner,   circuit means connecting said resistance means across said power source and including means operative to apply a predetermined voltage across said resistance means, and   means connecting the control electrode of said second switching means to one side of said resistance means.   
     
     
       2. The control system claimed in claim 1 in which said circuit means connecting said variable resistance means across said power source includes a manually variable resistance means operative to selectively apply predetermined voltages across said temperature variable resistance means. 
     
     
       3. The control circuit claimed in claim 1 in which means responsive to the existence of pilot flame comprises spaced electrodes arranged to be enveloped by pilot flame connected between one side of said power source and ground, and amplifying means responsive to flame conduction between said electrodes operative to apply a signal voltage to the electrode of said first switching means to effect its conduction. 
     
     
       4. The control system claimed in claim 1 which further includes a manually operable rotary valve controlling the flow of fuel to said main burner, and means rotating with said valve operative to vary the voltage across said temperature variable resistance means. 
     
     
       5. The control system claimed in claim 1 further including a manually operable rotary valve controlling the flow of fuel to both main and pilot burners, and electrically operated ignition means operative to ignite said pilot burner. 
     
     
       6. The control system claimed in claim 5 including a line switch operative to connect and disconnect the entire system with said power source, and means rotating with said rotary valve operative to actuate said line switch. 
     
     
       7. In a control system for gas oven burners, a source of a.c. electrical power,   a pilot burner,   a main burner,   a manually operable rotary valve controlling gas flow to both burners,   a main valve controlling gas flow to said main burner,   electromagnetically operated means controlling operation of said main valve including an electromagnetic winding,   electrically operated ignition means operative to ignite said pilot burner,   circuit means connecting said electromagnetic winding across said power source including a diode, a controlled solid state switching means, and a resistor,   said resistor being operative to limit the energization of said electromagnetic winding when said switching means is conducting to a level sufficient to maintain said main valve open but insufficient to effect the opening thereof,   means responsive to flame at said pilot burner operative to effect conduction of said switching means,   a storage capacitor connected in parallel with said electromagnetic winding and said switching means and in series with said resistor and said diode,   said storage capacitor being operative to attain a sufficient charge in a predetermined time during which said switching means is not conducting to effect, upon its discharge through said parallel connected electromagnetic winding, sufficient energization thereof to cause the opening of said main valve,   said storage capacitor being prevented from attaining a charge sufficient to cause opening of said main valve when said switching means is conducting,   a line switch operative to connect and disconnect said system from said power source, and   means moving with said rotary valve operative to acutate said line switch.   
     
     
       8. The control system claimed in claim 7 which further includes means responsive to directional changes in oven temperature operative to effect conduction and non-conduction of said switching means. 
     
     
       9. In an electrically operated control system for gas oven burners, a source of electrical power,   a pilot burner,   a main burner,   a manual valve controlling gas flow to both burners,   an electrically operated main valve controlling gas flow to said main burner,   electrical ignition means for igniting said pilot burner,   control circuit means controlling operation of said electrically operated main valve including switching means responsive to pilot flame and temperature responsive switching means responsive to oven temperature changes,   adjusting means for said temperature responsive switching means operative to vary the temperature point at which said temperature responsive switching means responds,   a line switch for connecting and disconnecting the system with said power source,   means movable with said manual valve for actuating said line switch, and   means operatively connecting said adjusting means with said manual valve.   
     
     
       10. The control system claimed in claim 9 in which said switching means responsive to pilot flame compreses a controlled solid state switching means, spaced electrodes arranged to be enveloped by pilot flame, circuit means operative to apply a predetermined voltage across said electrodes, and amplifying means responsive to conduction across said electrodes through pilot flame operative to apply a signal voltage to the control electrode of said switching means to effect its conduction. 
     
     
       11. The control system claimed in claim 9 which further includes means responsive to pilot flame operative to cut off operation of said electrical ignition means. 
     
     
       12. In a control system for fluid fuel burners, a source of electrical power,   a pilot burner,   a main burner,   a manually operable valve controlling fuel to both burners,   a main valve controlling fuel flow to said main burner,   electromagnetically operated means controlling operation of said main valve including an electromagnetic winding,   electrically operated ignition means operative to ignite said pilot burner,   circuit means connecting said electromagnetic winding across said power source including a controlled solid state switching means and a resistor,   said resistor being operative to limit energization of said electromagnetic winding to a level sufficient to maintain said main valve open but insufficient to effect the opening thereof,   means responsive to flame at said pilot burner operative to effect conduction of said switching means,   a storage capacitor connected in parallel with said electromagnetic winding and said switching means and in series with said resistor,   said storage capacitor being operative to attain a sufficient charge in a predetermined time during which said switching means is not conducting to effect, upon discharge thereof through said parallel connected electromagnetic winding, a sufficient energization of said winding to cause the opening of said main valve,   said storage capacitor being prevented from attaining a sufficient charge to cause the opening of said main valve when said switching means is conducting,   a line switch operative to connect and disconnect said system from said power source, and   means moving with said manually operable valve operative to actuate line switch.   
     
     
       13. In a control system for fluid fuel burners, a pilot burner,   a main burner,   a first valve controlling fuel flow to both burners,   a second valve controlling fuel flow to said main burner,   electrically operated means controlling operation of said second valve,   circuit means including first controlled solid state switching means operative when conducting to connect said electrically operated means across said power source,   spark ignition means operative to ignite said pilot burner,   said spark ignition means including storage capacitor means operative upon discharge thereof to provide a spark producing pulse and second controlled solid state switching means controlling discharge of said storage capacitor,   resistance-capacitance circuit means operative to periodically gate said second switching means to effect discharge of said storage capacitor,   gating circuit means for said first switching means including spaced electrodes arranged to be bridged by pilot flame and operative when pilot flame exists to effect conduction of said first switching means, and   shunting circuit means connecting said spaced electrodes in parallel with said resistance capacitance circuit means and operative when pilot flame exists to render said resistance capacitance circuit means inoperative to gate said second switching means.   
     
     
       14. The control system claimed in claim 13 in which said gating circuit means for said first switching means includes circuit means connected in parallel with said resistance capacitance circuit means operative to shunt said resistance capacitance circuit means operative in parallel with said resistance capacitance circuit means operative to shunt said resistance capacitance circuit and prevent gating of said second switching means.